Find the perfect time to go to bed or wake up, based on 90-minute sleep cycles — plus a personal plan for tonight.
What time do you want to wake up?
We'll find the best times to fall asleep.
Going to bed right now?
The time is
Most adults fall asleep in 10–20 min.
Cycles usually last 80–110 min.
A simple routine to fall asleep on time.
Check your sleep debt, discover your chronotype and fall asleep faster with built-in sleep sounds.
How much sleep did you get last week?
5 quick questions · 30 seconds
Rain, fan, calm music and soothing noise, generated right in your browser. No downloads, no lyrics.
Most sleep calculators give you a list of times and stop there. We help you actually hit them.
You sleep in repeating cycles of about 90 minutes. Waking up at the end of a cycle — not in the middle of deep sleep — is the secret to waking up refreshed.
Enter when you need to wake up, when you'll go to bed, tap “Sleep now”, or plan a nap.
We add the time it takes you to fall asleep (15 min by default) and count in full sleep cycles.
Pick a time, save a reminder, and follow tonight's plan to fall asleep on schedule.
Each cycle moves through light sleep, deep sleep and REM sleep. Early in the night you get more deep sleep; toward morning, REM periods get longer.
A few minutes of drifting off. Easy to wake.
Heart rate and temperature drop. About half the night.
Body repair. Waking here causes grogginess.
Memory and learning. Then a new cycle begins.
Recommended hours of sleep per day by age, according to the CDC.
| Age group | Age | Recommended sleep |
|---|---|---|
| Newborn | 0–3 months | 14–17 hours |
| Infant | 4–12 months | 12–16 hours* |
| Toddler | 1–2 years | 11–14 hours* |
| Preschool | 3–5 years | 10–13 hours* |
| School age | 6–12 years | 9–12 hours |
| Teen | 13–18 years | 8–10 hours |
| Adult | 18–60 years | 7 or more hours |
| Adult | 61–64 years | 7–9 hours |
| Older adult | 65+ years | 7–8 hours |
*Including naps. Source: Centers for Disease Control and Prevention (CDC).
The right nap length depends on what you want from it. Use the “Nap” tab above to get your exact alarm time.
| Nap length | What it does | Verdict |
|---|---|---|
| 10–20 min | Power nap: quick boost in alertness and mood | Best for most |
| 30 min | Often ends in deep sleep, so you may wake up groggy | Avoid |
| 60 min | Includes deep sleep — can help memory, but grogginess is common | Use with care |
| 90 min | One full cycle with REM — helps creativity, less grogginess | Great if you have time |
Good timing works best with good habits.
Same bedtime and wake-up time every day — weekends too.
Put your phone away 30–60 minutes before bed.
Caffeine can stay in your body for many hours.
Use blackout curtains, a fan or calm background noise.
Daylight soon after waking helps set your body clock.
Exercise helps — finish hard workouts a few hours before bed.
A sleep calculator suggests the best times to go to bed or wake up based on 90-minute sleep cycles, so you wake up at the end of a cycle instead of during deep sleep.
Eight hours isn't a multiple of a 90-minute cycle, so your alarm may go off during deep sleep. That heavy, groggy feeling is called sleep inertia. Try 7.5 or 9 hours instead.
Most sleep cycles last 80–110 minutes, with 90 minutes as a common average. You can change the cycle length in “Personalize” if yours is different.
Most adults need 5 to 6 full cycles a night — about 7.5 to 9 hours of sleep.
It depends on when you need to wake up. Count back 5 or 6 cycles plus about 15 minutes to fall asleep. For a 7:00 AM alarm, that's 11:15 PM or 9:45 PM.
About 10–20 minutes. It gives you a boost without dropping into deep sleep. If you have more time, a 90-minute nap covers one full cycle.
Sleep debt is the difference between the sleep you need and the sleep you actually get. Use the sleep debt calculator above to check yours.
It's a helpful guide based on average sleep cycles. Everyone's cycles vary a little, so use the results as a starting point and adjust to how you feel.
Find your perfect bedtime in seconds. Free, no sign-up.
🌙 Calculate my bedtimeThis tool is for general information only and is not medical advice. If you have ongoing trouble sleeping, talk to a doctor.